US5917669A - Method for transferring operational data between stations during a disk format process - Google Patents
Method for transferring operational data between stations during a disk format process Download PDFInfo
- Publication number
- US5917669A US5917669A US08/698,564 US69856496A US5917669A US 5917669 A US5917669 A US 5917669A US 69856496 A US69856496 A US 69856496A US 5917669 A US5917669 A US 5917669A
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- United States
- Prior art keywords
- disk
- station
- recited
- servowriter
- operational data
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/12—Formatting, e.g. arrangement of data block or words on the record carriers
- G11B20/1217—Formatting, e.g. arrangement of data block or words on the record carriers on discs
Definitions
- the invention relates to disk formatting using a servowriter. More particularly, this invention relates to methods of passing disk specific information from a servowriter to other downstream processes by recording the information on the disk during the servowrite process.
- a magnetic disk is commonly used in computer systems as a data storage medium.
- the disk must be formatted.
- the typical magnetic disk may be formatted to contain thousands of "tracks" of information, organized as concentric rings on the disk surface. These tracks must be precisely followed by the disk drive's read/write electronics during the operation of the disk to store information to and read information from the disk's surface.
- the read/write electronics follow the tracks via servo sectors embedded at regular intervals around the track.
- the tracks are pre-recorded on the disk surface in a factory environment before the disk is suitable for use in a disk drive.
- Each blank disk is prepared for use by a device commonly referred to as a "servowriter.”
- the servowriter is a machine dedicated to embedding servo signals into the disk's surface. After the servowriter has recorded the servo information in the servo sectors, the disk is checked for quality (e.g., by verifying the accuracy of the servo information). In some instances, for example where the disks are used in removable media drives, the verification process occurs at a separate time and place from the servowriting process at a device sometimes referred to as a verifier.
- the servowriter and the verifier need the same data with regard to a particular disk.
- One particularly important example is the identification of the servowriter used to format a disk. This information is readily available at the time of the disk format. However, after the disk is removed from the servowriter and moved to a different location, the identity of the formatting servowriter may not be readily apparent. This identity becomes significant because, at times, a defective or poorly calibrated servowriter will introduce errors into the formatting process. Unfortunately, in the case of removable media disks, the errors may not be discovered until the disks are checked by the verifier. Tracking the servowriter is difficult because disks are prepared by numerous servowriters. Moreover, those servowriters may be located at a number of different locations.
- Some disk manufacturers have used bar codes to trace the disks back to the servowriters and to provide other disk specific information. However, this requires some means for affixing a bar code to the disk, requiring an additional layer of expense and complexity. For example, attaching a bar code will add to the cost of producing each disk, or expensive equipment may be needed to properly track the disks. Moreover, an additional bar code scanning step may be required at the verifier.
- An additional example of data needed by both the verifier and the servowriter is media type.
- a variety of vendors may supply media readable by the same disk drive. Significantly, each of those media may have different characteristics that the verifier, and eventually a user's drive, should recognize. This media type information is also needed by the servowriter during the format process. Applicants have recognized that entering the data once, at the servowriter, and passing the data to the verifier would lead to fewer errors and higher quality.
- the present invention meets the needs above by providing a method of recording the disk specific data (hereinafter "operational data") on each disk during the servowriter process and retrieving that information during verification.
- operation data disk specific data
- a blank magnetic disk is formatted at a first station, e.g., a servowriter. While at the first station, an electromagnetic signal indicative of the operational data to be passed is embedded into the magnetic surface of the disks.
- the disk is then transported to a second station, e.g., a verifier. While the disk remains at the second station, the electromagnetic signal indicative of the operational data to be passed is retrieved off of the disk surface.
- the operational data is embedded in a guard band track.
- the operational data is inserted into a grey code field in the guardband track.
- the operational data it is necessary to record the operational data in a more accessible location on the disk. Accordingly, in some instances, after the disk is transported to the second station, the operational data is moved to a second location on the disk, for example, the Z-track.
- the operational data comprises a station identifier indicative of the formatting servowriter.
- a blank disk is initially formatted on a servowriter, wherein a servowriter station identifier is recorded on the disk. Thereafter, the disk is verified on a verifier.
- the verifier reads the servowriter station identifier and uses that identifier to trace the performance of each servowriter.
- a servowriter quality value maintained for each servowriter, is increased.
- the corresponding servowriter quality value is decreased.
- FIG. 1 depicts a magnetic disk and shows the location of format information
- FIG. 1A is a block diagram of a servowriter and verifier disk format configuration
- FIG. 2 depicts a portion of a magnet disk showing details of the servo sectors and data sectors
- FIG. 3 is a flow chart of the magnetic disk format process wherein the present invention may be employed.
- FIG. 4 is a flow chart of the verification process wherein the present invention may be employed.
- FIG. 1 a method for recording information on disks during the servowriting process and recovering that information during the verification process will now be described with reference to the FIGURES.
- the description given herein with respect to those FIGURES is for exemplary purposes only and is not intended in any way to limit the scope of the invention.
- the number of tracks per disk, sectors per track and the like are used to illustrate the invention.
- such examples are merely for the purpose of clearly describing the method of the present invention and are not intended to limit the invention.
- example applications are used throughout the description wherein the present invention is employed in conjunction with a particular disk drive system. That disk drive system application is not intended to limit the invention, as the invention is equally applicable to other systems.
- FIG. 1 depicts a magnetic disk 10 for use in a disk drive system (not shown) wherein the present invention may be employed.
- the magnetic disk 10 shown may be one of several different types.
- the present invention may be employed with a magnetic disk 10 for a ZIP drive or JAZ drive cartridge, both of which are manufactured by IOMEGA corporation, the assignee of the present invention.
- the disk drive system In order for the disk drive system to be able to access the magnetic disk 10 and read from and write to the disk 10, the disk 10 must be formatted.
- a number of concentric tracks 11 must be defined over the surface of the disk 10. These tracks 11 are defined by the use of servo sectors 16. Each track 11 has a fixed number of servo sectors 16.
- a JAZ disk for example, has servo sectors 16 sixty times per track 11 or every six degrees. Thereafter, when the disk 10 is used by a disk drive, the disk drive read/write electronics can read the servo sectors 16 and use that information to precisely follow the tracks 11 via a servo-loop.
- the disk 10 must be subdivided into good sectors and tracks and bad sectors and tracks, i.e., those sectors and tracks that cannot be reliably used during operation, must be located and flagged. In the case of ZIP and JAZ disk cartridges, this information is placed onto a special track called the Z-track.
- the disk 10 includes guard band tracks 12 at the innermost 12b and outermost tracks 12a. In general, these guard band tracks 12 are the same as all of the other tracks 11 on the disk. However, the disk drive electronics can determine whether a particular track 11 is part of the guard band 12 by the greycode number assigned to the track 11. In this manner, these guard band tracks 12 protect the disk drive read/write subsystem from traveling too far in or too far out during operation.
- the format process is performed in two major steps. As shown in FIG. 1A, the first step in the format process is performed by a servowriter 50.
- the servowriter 50 is a finely calibrated formatting device that places servo sectors 16 at precise intervals on the surface of the disk 10.
- a servowriter 50 comprise a spindle 51 for holding a disk 10 and spinning it up to operational speed; a read/write head 52 for writing and reading servo information to and from the disk 10; an arm 54 for moving the head 52 across the disk surface; an actuator 55 for controlling movement of the arm 54; a controller 58 for executing and controlling the servowriting process; and read/write electronics 56 for translating the electromagnetic signals of the disk surface to and from a digital format that is understood by the controller 58.
- the servowriter 50 comprises an input device, such as a keyboard, so that a servowriter operator can input information to control the servowriter process. Skilled artisans will appreciate that the servowriter 50 used to practice the present invention can be one of many commercially available units, such as Phase Metric/Helios MS 5000, appropriately modified to accept a particular variety of disk 10.
- the disks After the disks are formatted with the servowriter 50, they are transported to a verifier 60 as indicated by dashed line 70 to undergo a verification step.
- the verifier 60 checks each disk 10 by writing data to the disk 10 and reading the data back.
- the verifier 60 is simply a removable media disk drive, e.g., a ZIP or JAZ drive.
- the drives are modified to have special software designed to exercise the disk 10 by writing test data to it and reading the test data back from it.
- the major components of the verifier 60 are presented in block diagram form in FIG. 1A.
- the verifier 60 comprises a controller 68 that controls the verification process that is executed on the verifier 68; read/write electronics 66 for translating data to and from the magnetic signals embedded in the disk surface; a read/write head 62 for reading and writing magnetic signals to or from the disk surface; an arm 64 for suspending and moving the read/write head 62 on the disk surface; an actuator 65 for moving the arm 64 in response to commands from the read write electronics 66; and a spindle 61 for rotating the disk 10 at operational speed.
- the format process performed by the servowriter 50 is checked and any sectors or tracks that cannot be read from or written to are flagged.
- the servowriter process and the verifier process occur at different stations 50, 60. Moreover, those stations may be at geographically separate locations. As a result, information available at the time of the servowriting process, such as media type, servowriter station and the like, will have to follow the disks 10 between stations. Furthermore, any errors that occur at the verifier 60 must be traced back to the servowriter 50 so that servowriter 50 induced errors can be corrected. Consequently, each disk 10 must be tagged with a variety of information so that the disks 10 can be identified throughout the format process and, perhaps, throughout its useful life.
- operational data for each disk 10 is inserted onto the disks 10 during the servowriter process by the servowriter 50. Thereafter, the verifier 60 recovers the operational data written onto the disk by the servowriter 50.
- the servowriter 50 embeds the operational data in the servo sectors 16 of the guard band tracks 12. Thereafter, when the operational data is recovered by the verifier 60, the information may be moved to a data sector 17 for more permanent storage, as different applications of the present invention may require.
- each servo sector 16 is comprised of an automatic gain control (AGC) 22, overhead pad 24, greycode 26 and norm/quad fields 28.
- AGC automatic gain control
- servowriters 50 may not be capable of writing data in the conventional data sectors 17 of the disk 10.
- the servowriter 50 is capable of writing lower frequency information in the servo sectors 16. Importantly, that information is readable by the verifier 60. Thus, according to a presently preferred embodiment of the present invention, the servowriter 50 writes data to be recovered by the verifier 60 into the servo sectors 16 of the disk 10. As will be described in detail below, in one example application, the information replaces several of the greycodes 26 in the tracks of the guard band of the disk 10.
- the present invention relates to the broad concept of a servowriter 50 writing operational data in the low frequency servo sectors 16 of a disk 10 and recovering that operational data at the verifier 60.
- information readily available at the servowriter 50 does not have to separately follow each disk 10; rather, the information is embedded directly onto the disk 10, and as such automatically follows the disk 10 to the verifier 60.
- the information could be written to the greycodes 26 as well as other servo sector 16 fields.
- a data area on the disk 10 could be used and the drive could be modified to read the appropriate frequency.
- numerous applications for the transferred operational data are possible.
- servowriter station identifiers could be written to each disk 10 and used to monitor the quality of each servowriter 50.
- the process of recording operational data to disks 10 at the servowriter 50 begins by mounting a disk 10 on the servowriter 50, spinning the disk 10 up to operational RPMs and loading the heads 52 onto the disk surface (step 102). After the heads 52 are loaded onto the disk surface, they begin to move across the surface writing tracks 11 via servo sectors 16 and embedding greycodes 26 as track identifiers within each servo sector 16 of each track 11. The heads 52 continue this process moving across the entire disk surface until all the tracks 11 are written. Since the greycode 26 is the track identifier, it is incremented for each successive track 11.
- Each servo sector 16 contains a grey code field 26.
- this greycode field 26 contains the track number.
- the grey code is used to locate a track 11 when data from a particular track 11 is requested and is used to insure that the read/write heads remain on the proper track 11.
- the guard band 12 the tracks 11 are not used during the normal operation of the disk drive.
- this guard band 12 greycode information can be modified with no potential impact on the operation of the drive. Accordingly, during the servowriter process, the operational data is inserted into a selected group of the greycode fields 26 within the guard band 12.
- the servowriter process determines if the current track 11 is one of the tracks 11 to receive a special greycode (i.e. the operational data) (step 104). If not, the servowriter process continues normally, inserting servo sectors 16 with greycodes representative of the track number (step 106). On the other hand, if this is a special greycode track, e.g., within the guard band 12, then the operational data is inserted in the servo sector 16 in place of a normal greycode (step 108).
- a special greycode i.e. the operational data
- the next one-third of the track (i.e., 120 degrees) is written with the normal greycode inserted into the greycode field 26 (step 110). This process continues until the track 11 is completed (step 112). Consequently, when each special greycode track is completed, it will have three servo sectors 16, spaced apart 120 degrees around the track, each of which servo sector 16 contains operational data rather than the greycode. By contrast, the remaining servo sectors 16 for the same track 11 will contain normal greycodes.
- This servowriting process continues until all tracks 11 have been formatted (step 114). When the process is completed the heads are unloaded, the spindle stops and the disk 10 is released (step 116). The formatted disks 10 are then transported to a verifier 60 where they are quality tested.
- the operational data is extracted from the special greycode fields 26. In some instances, the operational data will also be saved as data on a different location on the disk (i.e. the tracks known as the Z-tracks). To begin the verification process the disks 10 are inserted into the verifier 60.
- a flow chart of the operational data extraction portion of the verification process begins when a disk is inserted into a verifier 60. Thereafter, the verifier 60 is commanded to seek to the inner guard band tracks 12b (step 1002), and a count is initialized to zero (step 1004). Starting with the first track 11 of the inner guard band 12b, all greycodes are extracted (step 1006). In a presently preferred embodiment, the operational data to be recovered is repeated in three greycode fields 26 within the same track 11. As a result, those three greycode fields 26 will not match the current guard band track number. Thus, to locate the special greycodes, each greycode is checked against the current track number (step 1008).
- the greycode is saved as a special greycode (i.e., it is possibly operational data) (step 1010), and the count is incremented (step 1012). If this is the last expected special greycode, e.g., the third one, then the check is finished (step 1014-1016) and the operational data has been recovered. Otherwise, this is not the last special greycode, and the checking of greycodes continues (step 1014-1018). After the three special greycodes are found, they are compared against one another as an error check. That is, the greycodes found that do not match the current track number should match each other. If there is a mismatch between the special greycodes, then an error has occurred, and the operational data cannot be recovered from this track 11 (steps 1020-1022).
- step 1024-1026 If the greycode has not been recovered from the preceding track 11 and the track number is still within the range of the guard band 12b, an attempt is made to retrieve operational data from the next available guard band track 11 (steps 1024-1026), and the steps above are repeated. If the next track 11 is beyond the range of the guard band 12b, a failure condition occurs (steps 1024-1028). In such a failure case, the operational data cannot be recovered.
- This process describes how a single piece of operational data is inserted at the servowriter 50 and recovered at the verifier 60. Obviously, this process could be slightly modified to insert and recover multiple pieces of operational data.
- the operational data is used to track and control the quality of the servowriter 50.
- the verifier 60 must know the identify of the servowriter 50 that formatted each disk 10.
- multiple servowriters 50 simultaneously format batches of disks 10. Those disks are then transported to multiple verifiers 60.
- each disk 10 is tagged during the servowriting process with an identification of the servowriter that formatted that disk.
- this servowriter identifier (i.e., the operational data) will be recorded in place of the greycode field 26 within several servo sectors 16. Thereafter, the servowriter identifier mark can be recovered at the verifier 60 during the verification process.
- the servowriter 50 When the servowriter 50 has been identified it is written to the disk 10 as data on the Z-tracks. Moreover, the servowriter identifier can be save in a database file so that servowriter confidence and yields can be tracked. Faulty servowriters are then determined based on a confidence value. In particular, if a particular servowriter confidence value falls below a threshold, the servowriter 50 is shut down. The servowriter confidence value is determined by the number of consecutive passes and fails for a particular servowriter.
- the confidence value is reduced by 10% for each fail and increased by 5% for each pass.
- a few failures rapidly reduced the confidence value.
- a second application of the present invention transfers media type between the servowriter and the verifier.
- the blank magnetic disks may be produced by a variety of manufacturers. As a result, disk characteristics may vary.
- the media type is determined during the servowriter stage, when the media first arrives from the media vendors. Accordingly, when the servowriter formats a disk, media type is inserted onto the disk as the operational data (i.e., via the greycode). Thereafter, when the disk is verified, the media type is extracted, used by the verifier and then copied to the Z-track for use by a user's drive.
- the operational data could merely contain a unique disk identifier.
- data for each disk can be stored in a database and retrieved by the servowriters 50 and verifiers 60.
- the techniques described herein are not limited to tracing servowriters during the disk format process. Other uses for the methods disclosed are possible.
- the disks could be traced during their useful life and high in-use failure rates identified. Accordingly, the scope of the invention is not intended to be limited by the preferred embodiment described above but only by the appended claims.
Abstract
Description
Claims (27)
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/698,564 US5917669A (en) | 1996-08-15 | 1996-08-15 | Method for transferring operational data between stations during a disk format process |
PCT/US1997/013853 WO1998007144A1 (en) | 1996-08-15 | 1997-08-06 | Method for transferring operational data between stations during a disk format process |
TW086111752A TW356539B (en) | 1996-08-15 | 1997-08-15 | Method of transferring operational data between stations during a disk format process |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/698,564 US5917669A (en) | 1996-08-15 | 1996-08-15 | Method for transferring operational data between stations during a disk format process |
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US5917669A true US5917669A (en) | 1999-06-29 |
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US08/698,564 Expired - Lifetime US5917669A (en) | 1996-08-15 | 1996-08-15 | Method for transferring operational data between stations during a disk format process |
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US (1) | US5917669A (en) |
TW (1) | TW356539B (en) |
WO (1) | WO1998007144A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6239937B1 (en) * | 1997-09-22 | 2001-05-29 | Seagate Technology Llc | Adaptive last-track positioning scheme for hard-disk drive formatting |
US6337779B1 (en) * | 1997-08-28 | 2002-01-08 | Sony Corporation | Disc-like recording medium, disc drive, and method for reading disc-like recording medium |
US6433948B1 (en) * | 1998-02-20 | 2002-08-13 | Samsung Electronics, Co., Ltd. | Process management method using servo track writer |
US6445531B1 (en) | 1998-10-09 | 2002-09-03 | Seagate Technology Llc | Disc drive method and apparatus for dynamically adjusting seek operations |
US6697208B2 (en) | 2001-08-22 | 2004-02-24 | Iomega Corporation | System and methods for using offset information on a data storage medium |
US6717758B2 (en) * | 2001-05-15 | 2004-04-06 | Iomega Corporation | Disk partitioning to create a usable, lower capacity disk cartridge |
US20110304935A1 (en) * | 2010-06-10 | 2011-12-15 | Samsung Electronics Co., Ltd. | Floating guard band for shingle magnetic recording |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999065025A1 (en) * | 1998-06-12 | 1999-12-16 | Iomega Corporation | Method and apparatus for enabling/disabling drive features |
TW454175B (en) * | 1998-10-30 | 2001-09-11 | Iomega Corp | System and method for protecting and securing a media verifier |
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-
1996
- 1996-08-15 US US08/698,564 patent/US5917669A/en not_active Expired - Lifetime
-
1997
- 1997-08-06 WO PCT/US1997/013853 patent/WO1998007144A1/en active Application Filing
- 1997-08-15 TW TW086111752A patent/TW356539B/en active
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6337779B1 (en) * | 1997-08-28 | 2002-01-08 | Sony Corporation | Disc-like recording medium, disc drive, and method for reading disc-like recording medium |
US6239937B1 (en) * | 1997-09-22 | 2001-05-29 | Seagate Technology Llc | Adaptive last-track positioning scheme for hard-disk drive formatting |
US6433948B1 (en) * | 1998-02-20 | 2002-08-13 | Samsung Electronics, Co., Ltd. | Process management method using servo track writer |
US6445531B1 (en) | 1998-10-09 | 2002-09-03 | Seagate Technology Llc | Disc drive method and apparatus for dynamically adjusting seek operations |
US6717758B2 (en) * | 2001-05-15 | 2004-04-06 | Iomega Corporation | Disk partitioning to create a usable, lower capacity disk cartridge |
US6697208B2 (en) | 2001-08-22 | 2004-02-24 | Iomega Corporation | System and methods for using offset information on a data storage medium |
US20110304935A1 (en) * | 2010-06-10 | 2011-12-15 | Samsung Electronics Co., Ltd. | Floating guard band for shingle magnetic recording |
US8179627B2 (en) * | 2010-06-10 | 2012-05-15 | Seagate Technology International | Floating guard band for shingle magnetic recording |
Also Published As
Publication number | Publication date |
---|---|
TW356539B (en) | 1999-04-21 |
WO1998007144A1 (en) | 1998-02-19 |
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